Infantry rifle bullet



y 6, 1969 L. SIX ETAL 3,442,216

INFANTRY RIFLE BULLET FiledDec. a, 1967 /.2mm 0 70 7 Portion F B 1 E IF 9 4 2 j 14.8 mm

J-Z L r .5 Cylindrical 10 m m porlz'on E g 3 4 p United States Patent U.S. 'Cl.'102-92'.2 2 Claims ABSTRACT OF THE DISCLOSURE An infantry rifle bullet comprising a lead filled jacket made of deep drawn sheet metal and having a short cylindrical tail portion of predetermined wall thickness and a longer pointed ogival portion of a wall thickness which gradually increases from said tail portion toward the tip.

This application is a continuation-in-part of our copending patent application Ser. No. 506,905, filed Nov. 4, 1965, now abandoned.

The invention relates to improvements in infantry rifle bullets of the type comprising a metal jacket and a lead core with the metal jacket having a cylindrical tail, or guide, portion merging at its forwardly end into an ogival portion with a pointed tip portion.

Infantry ammunition must comply with several requirements. For ease of transportation it should be light in weight, and it should cause the least possible recoil impulse. An infantry rifle bullet should have a relatively long effective range and a comparatively great piercing power in protected targets. It should also cause the greatest possible shock effect on live targets. The long effective range is desirable not only for the reason of its destructive eflect upon the enemy, but also in order to create a demoralizing effect upon the enemy troops when the range of their own bullets for the return fire it not long enough. The great piercing power is required for effectively hitting armor plate, steel helmets, protective vests, wood, masonry and the like.

This multiplicity of requirements leads to compromises in the making of the bullet. It is an object of the invention to create a bullet which complies with the mentioned requirements to a much higher degree than the known bullets. This object is attained by a combination of the following features:

(a) the bullet caliber is about 5.56 mm.;

(b) the bullet has a slender aerodynamically favorable shape and a length of about 4.6 times the caliber, or more;

(c) the ratio of caliber to Wall thickness of the jacket is about 22:1 along the cylindrical tail portion, about 14:1 at the point where the tip portion of the ogival portion begins, and about 4.7:1 at the tip portion measured along the longitudinal axis of the jacket;

(d) the lead core is deformable in such a manner that the necessary twist or spin is transmitted to the bullet when passing through the rifled barrel of the rifle.

Heretofore, no bullet has become known which possesses all these features. In general, until now an infantry rifle bullet was employed which had a caliber of 5.56 mm. or more (the caliber of the NATO bullet is, for instance, 7.62 mm.). Only one bullet for infantry rifles has become known which has a caliber of 5.56 mm., namely an American bullet with a jacket made of tombac and a core of lead. The cartridge belonging thereto is 45 mm. long, weighs about 13 grams and causes a recoil impulse of .59 kg. sec. This American bullet produces at a distance of 1,200 meters :1 specifis bullet energy of 37 mkp./cm. and at a distance of meters enters beechwood to a depth of about 10 centimeters and pine to a depth of about 35 centimeters. At a distance of 600 meters, this American bul et no longer penetrates a steel helmet, The NATO bullet has a weight of about 25 grams and creates a recoil impulse of about 1.15 kg. sec. At a shot distance of about 100 meters, the depths of entering into beechwood and. pineof a NATO bullet'are the same as the ones of the American bullet having a caliber of 5.56 mm. The specific bullet energy of the NATO bullet at a distance of 1,200 meters is 79 mkp./cm.

The bullet of the present invention at a distance of 1,200 meters still has a specific bullet energy of 70 mkp./ cm. The bullet still penetrates a modern steel helmet at a distance of 700 meters. The bullet of the invention at a distance of 100 meters enters beechwood to a depth of 33 cm. and pine to a depth of cm. It creates a recoil impulse of .58 kg. sec.

When shooting at soap plates or blocks of moist clay, the bullet of the invention produced a cavitation which was below the one produced by the American bullet of 5.56 mm. caliber at a distance of 400 meters; but at a distance of 400 to 500 meters the cavitation caused by the bullet of the invention was substantially equal to the one caused by the American bullet. At still greater distances, however, the bullet of the present invention was superior to the American bullet, as far as producing cavitation is concerned. The bullet of the invention is also superior concerning the creation of a shock effect, since the shock effect at relatively short distances need not be overly great, but is very desirable at greater distances. When the bullet of the invention was compelled to penetrate a wooden board or a steel plate before entering moist clay, the produced cavitation was always greater than the one caused by the American bullet.

The accompanying drawing shows by way of example a sectional view of the bullet of the invention and a portion of the cartridge therefor. For ease of description, the bullet is referred to as occupying an upright position with the tip portion uppermost.

Referring to the drawing, the steel jacket 1 surrounds the lead core 2 in such a manner that the lower end face 3 of the core 2 is engaged by an inwardly curved flange 4 of the cylindrical tail portion 5 of the jacket 1. A cylindrical neck portion 11 of the cartridge 8 has its upper end 6 somewhat restricted to engage an annular groove 7 in the jacket 1 at the upper end of its cylindrical portion 5.

The length of the cylindrical portion 5, including the groove 7, i.e. from A to D, is 10 mm., and the length of the ogival portion 9, from A to C, is 16 mm. The thickness of the tip portion 10 measured in the direction of the longitudinal axis of the bullet, i.e. from B to C, is 1.2 mm., thus making the distance from A to B 14.8 mm. and the total length of the jacket from D to C 26 mm.

As mentioned above, the nominal caliber of the bullet is 5.56 mm. which, of course, is the outer diameter of the jacket at A, i.e. at the bottom end of the ogival portion 9. This is also the inner diameter of the rifled barrel from which the bullet is to be fired, while the diameter of said barrel measured from the bottom of the helical groove therein is 5.70 mm. which is also the outer diameter of the cylindrical jacket portion 5 so that, when the bullet is fired through said rifle barrel, the helical rifle ridges therein impress themselves in the outer surface of the cylindrical portion 5 and thereby cause the bullet to spin about its longitudinal axis in a well known manner.

The wall thickness of the cylindrical portion 5 is 0.25 |m., the wall thickness of the ogival portion 9 is 0.3 mm. t the bottom end thereof, i.e. at the point A, and this wall iickness increases gradually and uniformly from the :vel A to the level B, where said wall thickness is 0.4 mm. will be seen that said level B is at the bottom end of the p portion of the ogive 9. For convenience, the portion of 1e ogive between A and B will be called the thin walled ortion of the ogival jacket portion, as distinguished from he thicker tip portion from B to C.

It will now be seen that the proportions between the .ominal bullet caliber and the several dimensions menioned above are as follows:

a) The wall thickness of cylindrical portion 5:5 .5 6:0.25 Jiiiiiiiu thickness of ogival portion 9 at A=5.56:0.3 jcT'l'ii viall thickness of ogival portion 9 at B=5.56:0.4 :d) 1 lii c k ness of tip portion 10 from B to C=5.56:l.2 IeT'lfitil length of bullet from C to D=5.56:26

Obviously, the proportions (a), (c) and (d) are in :uflicient agreement with the requirements recited in the irst portion of this discription, viz. 22:1, 14:1 and 4.7:1, .espectively. The total length of the bullet was given as tbOlll'. 4.6 times the caliber, i.e. 4.6 5.56=25.576 mm. which requirement also is satisfied.

It may be added that the ratio of the length of the :ylindrical portion 5 to the caliber is 10:5.56=1.8:1 and that of the length of the ogive to the caliber=16:5.56 =2.8Z1.

The cartridge 8 is 57 mm. long and weighs about 13 grams. The jacket is made of deep-drawn sheet metal and is provided with a plating of copper-nickel or tombac. The lead is alloyed with 2% antimony and under the thin wall of the jacket is deformable in just the correct manner that a very intense twist or spin may be transmitted to the bullet, which is very desirable in order to attain the de sired flight stability of the bullet.

It is within the scope of the invention to deviate to some extent from the exact values given above. It is, for instance, possible to make the wall thickness of the jacket at its tip somewhat greater and to decrease the wall thickness of the tail portion. The bullet may also be made somewhat longer as this would increase the range and the piercing power thereof. In doing this, the caliber of the bullet may be reduced without changing the effect. The lead may be alloyed with a different percentage of antimony, and also other alloy materials may be employed, as long as the deformability is such as to attain the required twist or spin which gives the bullet a suflicient flight stability. The cartridge length and filling may be adapted to the particular weapon which is to be used. The steel should be age resistant. During the making of the bullet, the steel is cold hardened.

What we claim is:

1. An infantry bullet, including a lead filled jacket made of deep drawn sheet steel and comprising a cylindrical tail portion merging into an ogival portion terminating in a point, the ratio of the bullet caliber to the wall thickness of the jacket being about 22:1 in said cylindrical tail portion, about 18.5:1 at the tail end of the ogival portion (at A) and gradually decreasing to about 14:1 at the tail end of the tip portion (at B), and about 4.7:1 at said tip portion measured along the longitudinal axis of the bullet, while the total length of the bullet is about 4.6 times said caliber.

2. An infantry bullet as set forth in claim 1, in which the length of said ogival portion (A to B) is about 2.8 times the caliber and the length of said cylindrical tail portion (A to D) is about 1.8 times said caliber.

References Cited UNITED STATES PATENTS 338,191 3/1886 Rubin 102-922 841,861 1/ 1907 Gleinich 1'0292.1 1,187,867 6/1916 Shinkle 10292.1 2,120,913 6/1938 Studler 102-923 2,322,751 6/1943 Studler 10292.3 FOREIGN PATENTS 462,031 11/1913 France.

ROBERT F. STAHL, Primary Examiner. 

